Various MEMS devices are becoming increasingly popular. MEMS transducers, and especially MEMS capacitive microphones, are increasingly being used in portable electronic devices such as mobile telephones, wearable devices and portable computing devices.
Microphone devices formed using MEMS fabrication processes typically comprise one or more membranes with electrodes for read-out/drive deposited on the membranes and/or substrate. In the case of MEMS pressure sensors and microphones the read out is usually accomplished by measuring the capacitance between the electrodes. In the case of output transducers, the membrane is moved by electrostatic forces generated by varying a potential difference applied across the electrodes.